The present invention relates to a liquid crystal matrix display device which uses thin film transistors (hereinafter referred to as TFT) as switching devices and particularly to a liquid crystal matrix display panel whose switching devices are reverse stagger type TFT devices using amorphous silicon as semiconductor film.
The typical structure of a liquid crystal matrix display device using reverse stagger type TFT as switching devices is shown in FIGS. 7(a) and 7(b). This liquid crystal display device comprises a gate electrode 103, gate insulation film 104, a-Si film 105, insulation film 106, n+ a-Si film 107, source and drain electrodes 108, a picture element electrode 109 and protective film 110 formed in lamination on an insulating substrate 101. Using glass as the insulating substrate 101 and tantalum (Ta) as the gate electrode 103, when the gate electrode 103 is patterned on the substrate by wet etching, the etchant of the tantalum attacks the glass, resulting in cloudy and/or rough glass surface. No improvement of this point has been proposed.